A known illumination device is equipped with a cooling fan and a light-emitting diode (LED) acting as a semiconductor light source. The cooling fan prevents the temperature of the LED from increasing as the result of heat generated by the LED. The illumination device also is mounted with a fan drive circuit that rotationally drives and controls the cooling fan, and with an LED drive circuit that drives and controls the LED.
The cooling fan is provided on a back surface of a plurality of LEDs and is equipped with a rotatable propeller. Wind generated by rotational driving of the propeller in the cooling fan is sent to the LED side, thereby preventing the temperature of the LED itself from increasing (see, e.g., Japanese Patent Application Laid-Open (Kokai) No. 2001-216803).
Application of the above illumination device to a vehicular lamp contributes to lengthening the life of the semiconductor light source and is, therefore, suitable for reducing the number of times the semiconductor light source must be replaced.